Bi-oleothermal process is a simple treatment which has been developped by CIRAD in cooperation with FCBA. It allows a deep impregnation of wood with hydrophobic products using cheap facilities. The process includes two steps at atmospheric pressure. The first one is a dipping of wood samples in a hot oil bath (between 110 °C and 200°C) which creates an overpressure inside the wood. The second one is also a dipping in a oil bath but at a lower temperature (20°C to 80°C). In this second bath samples cooling leads to water condensation. A vacuum is created inside the samples and makes the oil to impregnate the wood. In this study, this process has been used to impregnate several wood species with several linseed oils with and without biocides. The resistance to wood destroying fungi has been assessed using a method adapted from EN 113. Results show that the linseed oils lead to an increase in the natural durability. The resistance to termites and to house longhorn beetles has been assessed using EN 117 and EN 47 respectively. Wood treated with biocide-free oil is attacked by termites but afterwards the oil induces the death of the insects. The addition of biocide makes the wood completely protected from termites attacks. EN 47 results show that 93% of mortality amongst the beetles is obtained with the biocide-free oil and 100% with the oil including biocide. The resistance of the treatment to weather has been studied using artificial weathering test according to EN 927-6. Results show that the coating provided by this process constitutes a low performing product compared to conventional stains. However the coatability with a solventborne or a waterborne stain is ensured and leads to good performance after artificial weathering. The influence of the oil treatment on wood exposed to fire was studied on oil treated samples and on samples which were fireproofed and then oil treated. EN ISO 11925-2 tests show the oil treated samples do not pass the test and have a fire classification of F. However samples that have been fireproofed and then impregnated with the linseed oil pass the test and a fire classification of E is obtained. These results were completed with EN 13823 tests. Samples that were fireproofed then oil treated fulfill the C fire classificiation requirements.

Download document (364 kb)
free for the members of IRG. Available if purchased.

Purchase this document